The High Road : Double-Decking of Section of Harbor Freeway Is Latest Response to Area’s Traffic Nightmares

If driving the single-level Los Angeles freeway system leaves you white-knuckled, imagine what thrills await you when a second deck is added.

Double-decking, an idea once regarded as bizarre, now is receiving serious attention from traffic officials as congestion worsens and the prospect of building new freeways grows remote.

The California Department of Transportation expects to let initial contracts for double-decking 2.6 miles of the new Harbor Transitway before the end of the year. An elevated option also is being considered for a 20-mile stretch of the Ventura Freeway. And a recent Caltrans study concluded that double-decking might be appropriate on sections of the Santa Ana, San Diego and Santa Monica freeways as well.

“We’re running out of room,” said Jerry B. Baxter, Caltrans director in the Los Angeles area. “We’ve got to do something.”

A Matter of ‘What If’

Baxter emphasized that “no commitment has been made. . . . We’re still doing ‘what if’ studies.”

Double-decking becomes a stronger possibility, he said, as traffic volume soars, right-of-way becomes more difficult to acquire in urban areas and community opposition and environmental concerns combine to make construction of new freeways almost impossible.

He said Caltrans has increased freeway capacity by narrowing lanes, eliminating shoulders and by such “traffic management” techniques as ramp metering and “smart freeways”--electronic systems that detect accidents or other congestion and direct motorists to alternate routes. Little more can be done along those lines, he said.

“We look at those SCAG (Southern California Assn. of Governments) projections--a 60% increase in travel by the year 2010 or something like that--and we try to figure out how we can accommodate this as best we can,” Baxter added.

Used in Other Cities

Multilevel freeways and bridges are not new, of course. The Embarcadero Freeway in San Francisco, the Alaskan Way Viaduct in Seattle and the FDR Drive, along the East River in New York City, were built many years ago. And, the San Francisco-Oakland Bay Bridge and George Washington Bridge in New York City, among others, have two levels. But adding a second deck, either above or below the existing level of traffic, to increase capacity, is a relatively new thought and has been tried only in Austin, Tex., and one or two other places.

There is “considerable interest” in the Legislature in considering two-level freeways for “built-up areas where acquiring right-of-way is costly, lengthy and onerous,” said John Stevens, principal consultant to the Assembly Transportation Committee.

But double-decking is extremely expensive. It will cost about $85 million to $100 million to build 2.6 miles of elevated structures on the Harbor Freeway--out of a total $548 million cost for the entire 19.6-mile Harbor Transitway. Only the fact that the Harbor project is part of the Interstate Highway program and consequently is eligible for 90% federal support has made it possible.

The transitway project will add a single lane in each direction for buses and car pools (three or more to a car), between downtown and San Pedro, and is scheduled to open in late 1993. It is intended to relieve congestion on the Harbor Freeway, which currently carries about 230,000 vehicles a day and has a 50% higher accident rate than any other Los Angeles freeway.

‘Key Is Economics’

When Gov. George Deukmejian first announced the plan in 1984, it was thought that half of the Harbor Transitway would be elevated, but Caltrans engineers found they could fit most of the widening project into the existing right-of-way. Only in the two short sections near the central business district was it necessary to use double-decking.

“The key is economics,” said Dean Larson, assistant chief of the planning and design office for Caltrans in Sacramento. “Is it cheaper to buy property and widen the existing freeway or is it cheaper to go up in the air?”

The Santa Monica-based Reason Foundation, an independent research group, has proposed that upper decks be financed by tolls, an idea that has been supported by Los Angeles City Councilman Hal Bernson and others. The Reason Foundation also believes the toll facilities should be built and operated by private industry.

Caltrans officials said they are studying both proposals but have not endorsed them.

Environmental Problems

In addition to high cost, double-decked freeways also present environmental problems.

They are noisy--because traffic volumes are higher, speeds are greater and sound “reflects” from the new upper deck, the Caltrans study found. They also add to air pollution because of increased traffic volume and the accumulation of fumes on the lower deck.

The aesthetic disadvantages of high-speed, elevated expressways are another potential problem.

“We’re not quite sure what the community reaction will be when we start talking about building freeways 40 feet up in the air,” said Jim Sims, director of programming and fiscal analysis for the Los Angeles County Transportation Commission.

It is difficult to keep traffic flowing on the existing freeway while construction of a second deck is going on, a major consideration in the Caltrans decision to widen, rather than double-deck, the Santa Ana Freeway, said Keith McKean, the agency’s Orange County director.

Most work on the elevated sections of the Harbor Transitway will be done at night, said Charles J. O’Connell, the Caltrans deputy director in charge of the project. Still, it will be a “pretty good trick” to maintain regular freeway traffic flow while the work is under way, he added.

If double-decking simply moves a traffic bottleneck from one location to another, it is of little use, so Caltrans and the city of Los Angeles are working together on plans to feed traffic from the elevated structures onto city streets, but O’Connell said details of the plan are not yet available.

David Grayson, director of engineering and technical services for the Automobile Club of Southern California, said he has reservations about double-decked freeways because “they concentrate travel in a single (traffic) corridor, instead of two or more, you give up serving other urban land that may very well remain unserved.”

But Baxter replied: “That’s fine, but where do we find the land to do that? I don’t have any people breaking in my door to get a new freeway built.”

Focus on Traffic Control

Some critics believe more attention should be paid to traffic management--such measures as added incentives for car pooling and use of public transit, flexible work schedules and changes in truck delivery times--and less to building new structures of any kind.

Peter Gordon, associate dean of the School of Urban and Regional Planning at USC, called double-decking a “lunatic fringe example” of a general problem. “We quickly get locked into discussions of what we can build next, not how can we manage better what we already have,” he said.

He said “doomsday” forecasts that traffic congestion will increase steadily until average speeds on Los Angeles freeways drop below 20 m.p.h. are inaccurate because “cities adjust, people adjust” by changing jobs or working at home or moving away.

“Relocation as a response really implies that ‘doomsday’ or ‘gridlock’ will never really happen,” Gordon stated, “but the logic of the real world is missing in the model,” which then generates the dire predictions that cause planners to consider such steps as double-decking.

Many Caltrans officials agree that better traffic management is needed but they also believe some new facilities must be built and that a few multilevel freeways might be among them.

“There isn’t any big statewide move to a system of double-decked freeways, largely because of cost,” said Dean Larson of Caltrans’ Sacramento office, “but in certain circumstances, if the conditions are right, that might be just the thing to do.”